“Another intresting project to consider is the Arduino Watering System. Everyone has at least one plant in their room, kitchen or balcony. Is essential keep them fed and keep the soil moist, and if you don’t have a good memory this simple project will help you a lot.
Easy to understand and realize: you only need aa 5-9v pump, a soil moisture sensor (LM939 or v1.2), a relay module, and an Arduino Nano or UNO.
Here is a complete kit to get you started easly.
The soil moisture sensor value goes from 0 to 1023, when the sensor recive a value minor than 600, the relay turn on and the pump starts to irrigating the soil. To adapt the 220V home tension, i used a phone charger. Open it, remove the USB connector, find the VCC and GND pins (probably 1° and 4°) and connect it to the Arduino pins (like the wiring diagram)”